A friend of mine was active in Spec 7 / Pro 7 (1st gen. RX-7) and was researching Spec Miata. His research included signing up for various NASA, SCCA, and Miata forums. In one of these forums he ran into a challenge, an east coast Spec Miata racer wanted to challenge other racers and would let them select the track. A west coast guy offered up his challenge, set Laguna Seca to be the location and a date was set.

In the time between the challenge being issued and the race date, the east coast guy fired up Gran Turismo 3, built a Miata close to what one would find in Spec Miata and practiced on Laguna Seca. He beat the west coast guy on his own track and gave credit to GT3 helping to familiarize himself with the track.

I also saw a video where Nürburgring instructors had a guy race in a game (GT or FM) before his first time on the Nordschleife. His time was compared to other Nür rookies where he showed an improvement. It wasn't much though it helped.